1. Field of the Invention
This invention pertains generally to the field of synthetic vision systems such as, but not limited to, those employed in aircraft display systems.
2. Description of the Related Art
The synthetic vision system (“SVS”), enhanced vision system (“EVS”), and combined enhanced-synthetic vision system (“EVS-SVS”) are used to present to pilots of aircraft with egocentric, three-dimensional perspective images of the scene outside the aircraft. With respect to the SVS and EVS-SVS, the image may be generated using a terrain database that could also been employed by terrain awareness and warning system (TAWS”) meeting the standards published by the Federal Aviation Administration in a Technical Standard Order (“TSO”) known as TSO-C151 b.
Another database that could be employed in aircraft is airport database comprised of one or more airport mapping databases configured to store, in part, data representative of an elevation and location of an airport or aerodrome reference point and data representative of dimensions and locations of surface features such as, but not limited to, runways, helipads, taxiways, frequency areas, aprons, parking areas, and vertical structures located within an area defined as an airport and/or aerodrome. One such example of such airport database is described in industry standards published by Aeronautical Radio, Inc. (“ARINC”) and/or Radio Technical Commission for Aeronautics (“RTCA”) such as, but not limited to, ARINC Specification 816 entitled “Embedded Interchange Format for Airport Mapping Database” and RTCA DO-272A entitled “User Requirements for Aerodrome Mapping Information.”
Because the TAWS and ARINC 816 databases have been developed for different purposes, the use of both in combination of one another is not conducive when generating an egocentric, three-dimensional perspective image. Where the TAWS database is generally populated with terrain elevation values of a plurality of terrain cells, the ARINC 816 database is generally populated with one elevation value per airport. When an egocentric image of an airport is generated using data retrieved from a TAWS database, an image of a terrain surface that is neither flat nor even is typically produced because the real terrain on which an actual airport sits is comprised of a plurality of elevation values; however, when an egocentric image of an airport is generated using data retrieved from an ARINC 816 database, a terrain surface that is flat and even is generally produced because there is one elevation value. If a plurality of elevations are retrieved from the TAWS database and included with the surface features retrieved from the ARINC 816 database in the generation of the image, a loss of surface features could result.